1. Field of the Invention
The present invention relates to a die opening and closing system and die opening and closing method used for die cast machines and other molding machines.
2. Description of the Related Art
A die opening and closing system (clamping system) for making a moveable die plate by a ball-screw feed mechanism back advance and retract in a die opening and closing direction to open/close a die is known. Japanese Patent Publication (A) No. 2002-154146 discloses a die opening and closing system provided with two ball-screw feed mechanisms at symmetric positions on the two sides of the die opening and closing system. Japanese Patent Publication (A) No. 2002-225101 discloses a die opening and closing system provided with only one ball-screw feed mechanism. Note that a die opening and closing system for opening and closing a die by an oil pressure cylinder is also known.
A ball-screw feed mechanism is, in comparison to an oil pressure cylinder, generally accurately controllable, but has difficulty in obtaining a high drive force. As a result, for example, providing a ball-screw feed mechanism in a large die opening and closing system requiring a high drive force etc. will raise the initial costs. That is, in cases such as in Japanese Patent Publication (A) No. 2002-154146 where two ball-screw feed mechanisms are provided to obtain the drive force, the initial costs become higher than a case where there is one ball-screw feed mechanism, and, in cases such as in Japanese Patent Publication (A) No. 2002-225101 where one ball-screw feed mechanism is provided, the ball-screw feed mechanism becomes larger and loses its versatility, causing the ball-screw feed mechanism unit price to rise. Therefore, to achieve low costs while keeping the superiority in controllability of the ball-screw feed mechanism, it is necessary to reduce the load of the ball-screw feed mechanism.